"As for the compound, only its walls were partially destroyed and nobody was hurt inside," Rahimi said.

There were no immediate claims of responsibility.

Police do not allow trucks to enter the capital during the day; they can only enter the city between 9 p.m. and 5 a.m.

RFE/RL's Radio Free Afghanistan correspondent Sahar Lewal, who visited the scene of the blast in the morning, said the powerful explosion had damaged the bustling area beyond recognition.

"Siyah Sang was a busy neighborhood with private houses and many shops but this morning it looked like a ruin where nobody had lived for many years," the correspondent said.

"Cars were damaged, the roofs of houses and shops have collapsed, there wasn't one window with glass intact, and contents of shops were scattered everywhere," she said. "People were cleaning shattered glasses."

The correspondent said the power of the blast, which she estimated had left a 10-meter crater in the road, was felt in other areas of the city and could be heard several kilometers away.

Police said officials were searching for anyone trapped under the debris.

The attack came after the United Nations said in a report on August 5 that a growing number of women and children were being injured or killed in the ongoing conflict in Afghanistan.

The number of women casualties rose by 23 percent and children 13 percent in the first half of this year, compared to the same period last year, according to the UN report.